1. Field of the Invention
The invention relates to disposable, nonwoven, absorbent structures and particularly to such structures characterized by synergistic absorbency, excellent wet and dry bulk, low lint discharge and a cloth-like aesthetic.
2. Description of the Prior Art
The absorbent structures of the present invention have many applications and in fact may be used wherever their unique absorbency and wet and dry bulk characteristics would be advantageous. By careful selection of the materials constituting the alternate layers of absorbent nonwoven material and nonwoven hydrophobic thermoplastic material, the absorbent structures of the present invention may be engineered to serve many appropriate end uses.
While not intended to be so limited, the absorbent structures of the present invention will be described primarily in terms of their application as surgical sponges. The choice to so describe the absorbent structures has been made for two reasons. First of all, the absorbent structures of the present invention lend themselves particularly well to such surgical applications, and secondly, the requirements for such surgical applications are generally far more stringent than those for other applications.
Of the various types of known surgical sponges, one which is very commonly used is generally known as a laparotomy sponge, pad or strip. While its use is not necessarily so limited, the name of this type of sponge is derived primarily because it is extensively employed in laparotomy procedures involving entrance into the abdominal cavity through the abdominal wall. Laparotomy sponges have many applications, frequently involving introduction of the sponge into the wound or abdominal cavity. They are used, for example, to absorb large quantities of blood, body fluids or the like, to "wall-off" organs not involved in the surgical procedure and to assist in the handling of organs. Laparotomy sponges have hitherto most commonly been made of a plurality of plies of cotton gauze sewn together, or of gauze plies surrounding a core of absorbent material.
Laparotomy sponges made of cotton gauze are normally intended for reuse and are characterized by a number of disadvantages. First of all, gauze sponges are relatively expensive and, to achieve adequate absorbency, a relatively large number of gauze plies is required. Since such gauze structures are intended for reuse, this involves the time and expense of washing and sterilization together with the individual hand work required in sorting, folding and the like. Reusable structures always involve some danger of cross-contamination. Furthermore, cotton gauze structures of this type are subject to linting and lint, when left in a wound or in the body cavity, may lead to such post-operative problems as inflammation, adhesions and the formation of granulomas.
Despite these various drawbacks, cotton gauze sponges are characterized by good surface aesthetics inclusive of surface texture and hand. They also possess adequate wet and dry bulk. An exemplary cotton gauze laparotomy sponge is taught in U.S. Pat. No. 3,698,393, in the name of Charles E. Stone, issued Oct. 17, 1972. U.S. Pat. No. 3,837,344 in the name of Donald Patience, issued Sept. 24, 1974, sets forth a laparotomy sponge formed of a plurality of gauze plies, the yarns of each ply being kinked, convoluted and twisted into interengagement with the yarns of adjacent gauze plies. In U.S. Pat. No. 4,068,666, in the name of James A. Shiff, issued Jan. 17, 1978, a surgical sponge is taught having an absorbent core of natural or synthetic fibers surrounded by outer layers of gauze or other grid materials, such as nonwoven polyester material. Yet another woven cotton surgical sponge is illustrated in U.S. Pat. No. 3,965,907 in the names of David R. Hardy and Richard C. Weatherford, issued June 29, 1976. U.S. Pat. No. 3,971,381, in the name of Robert T. Gibson, issued July 27, 1976 sets forth a laparotomy sponge comprising a central core of mixed rayon and polypropylene fibers pressed into a batt and heat bonded. The batt is then given waffled surfaces by means of a knurled roll, the surfaces having a diamond pattern of alternate raised and depressed areas. This core material is surrounded by cotton gauze outer layers.
Prior art workers have turned their attention to the provision of disposable surgical sponges, attempting to equal or better the advantages of gauze sponges, while overcoming their disadvantages. U.S. Pat. No. 3,837,950 in the name of Harry G. Reimels, issued Sept. 24, 1974 teaches a surgical sponge for delicate surgical procedures comprising a relatively thin strip of nonwoven fibers securely bonded together by a mixture of starch and polyvinyl alcohol. A disposable absorbent sponge made up of a plurality of reinforced nonwoven textile fabrics is set forth in U.S. Pat. No. 3,683,921 in the names of Berry A. Brooks and Norman R. Eisdorfer, issued Aug. 15, 1972. Each reinforced nonwoven textile fabric layer comprises a synthetic polymeric thermoplastic reinforcing reticulate grid netting covered on each side by at least one layer of overlapping, intersecting fibers mechanically intertwined around and bonded to the individual elements of the grid netting. Surfactant treated polyurethane sponges are taught in U.S. Pat. No. 3,566,871 in the names of Ferdinand J. Richter and Charles T. Riall, issued Mar. 2, 1971 and in U.S. Pat. No. 3,961,629 in the name of the same inventors, issued June 8, 1976. Finally, in U.S. Pat. No. 3,867,935 in the names of Norman R. Eisdorfer, John M. Lesniak and Bernard M. Lichstein, issued Feb. 24, 1975, there is described a laparotomy pad comprising a plurality of plies of hydraulically entangled hydrophilic fibers interlayered with thin thermoplastic grids.
The disposable nonwoven structures and surgical sponges of the present invention are easily and inexpensively manufactured, are intended to be disposable and are free of the disadvantages possessed by prior art gauze structures. The disposable nonwoven absorbent structures of the present invention demonstrate excellent wet and dry bulk in combination with synergistic absorbency and cloth-like aesthetics. The phrase "cloth-like aesthetics" as used herein refers to softness, tactility, texture, appearance and other properties contributing to the overall impression of the material. Of particular importance in surgical uses is the fact that these nonwoven absorbent structures are essentially free of lint or particulate discharge. They are possessed of excellent drape, conformability, pliability and softness and are non-abrasive to delicate tissue. The hydrophobic thermoplastic layers can serve as a dry adhesive, enabling the structures to be minimally heat bonded. The structures, particularly when intended for surgical uses, are preferably free of additional bonding agents and other additives such as surfactants (including wetting agents), surface finishes and the like, which might leach into a wound.